1. Field of the Invention
The present invention concerns a gold wire for wire bonding used for connecting chip electrodes and external leads of a semiconductor.
2. Description of the Prior Art
For improving mechanical property and bonding property of gold wires for bonding, various kind of elements have been incorporated into Au at high purity of 99.99% or higher.
For instance, there have been known those bonding wires prepared by incorporating La, Pb, Be and Ca to Au at high purity (Japanese Patent Laid-Open Sho No. 62-228440), or a predetermined amount of La and Be to Au at high purity (Japanese Patent Laid-Open Sho No. 60-30158) and they have respective usefulness under certain conditions.
However, as the multi-pin arrangement has been adopted more and more in LSI packages in recent years, it has been required that wire loops in the form of bonding have greater length and height of loops as compared with conventional loops.
That is, it has been required that a loop height be maintained without causing sagging of the loop and that even a long loop has a property of not causing sweep, that is, high tensile strength at a ball neck portion (neck strength), large loop height and less wire bending.
In conventional gold wires, however, the foregoing requirements can not be satisfactorily achieved with known additive elements and the range of the content thereof and, accordingly, no improvement can be expected for the reliability of semiconductor devices.